Abstract
The intermittent energy restriction (IER) approach to weight-loss involves short periods of substantial (>70%) energy restriction interspersed with normal eating. Studies to date comparing IER to continuous energy restriction (CER) have predominantly measured fasting indices of cardiometabolic risk. This study aimed to compare the effects of IER and CER on postprandial glucose and lipid metabolism following matched weight-loss. 27 (13 male) overweight/obese participants (46±3y, 30.1±1.0kg/m2) were randomised to either an IER (2638 kJ for two days/week with an overall ER of 22±0.3%, n=15) or CER (2510kJ below requirements with overall ER of 23±0.8%) intervention. Six-hour postprandial responses to a test meal and changes in anthropometry (fat mass, fat-free mass, circumferences) were assessed at baseline and upon attainment of 5% weight-loss, following a 7 day period of weight stabilisation. The study found no significant difference in the time to attain a 5% weight loss between groups (median 59 [41-70] days and 73 [48-128] days respectively, p=0.246), or in body composition (p≥0.430). For postprandial measures, neither diet significantly altered glycaemia (p=0.226), whereas insulinaemia was reduced comparatively (p=0.903). The reduction in c-peptide tended (p=0.057) to be greater following IER (309128±23268 to 247781±20709 pmol.360min.L-1) versus CER (297204±25112 to 301655±32714 pmol.360min.L-1). The relative reduction in triacylglycerol responses was greater (p=0.045) following IER (106±30 to 68±15 mmol.360min.L-1) compared to CER (117±43 to 130±31 mmol.360min.L-1). In conclusion, these preliminary findings highlight underlying differences between IER and CER, including a superiority of IER in reducing postprandial lipaemia, which now warrant targeted mechanistic evaluation within larger study cohorts.